Photoelectric relay apparatus



Dec. 413, 1938. P. JUCHTER i PHOTOELECTRIC RELAY APPARATUS Filed March16, 1935 w Th mm nJ e vv Tm um/'nation 7Zzr/1ad Ufff Illumination 7r/7ed@n Patented Dec. 13, 1938 UNITED STATES PHOTOELECTRIC Pieter J uchter,Scotia,

PATENT OFFICE RELAY APPARATUS N. Y., assignor to General 'l Claims.

My invention relates to photoelectric relay apparatus and particularlyto that type of such apparatus which is arranged to operate in one sensewhen the value of the controlling light, in reducing, passes a certainvalue and to operate in the opposite sense when the value of the light,upon subsequently increasing again, passes the same or approximately thesame value. A common use for such apparatus is that of turning onartiiicial illumination such as street lighting in the late afternoon orevening when daylight has diminished to a predetermined low value and ofturning off the illumination in the morning when the returning daylightmakes the illumination unnecessary. With such apparatus as it has beenconstructed heretofore the value of daylight at which the illuminationwas turned oif in the morning was necessarily somewhat higher than thatat which the illumination was turned on in the previous evening. Incertain cases, however, it has been found desirable to turn off theillumination in the morning at a materially lower value of daylight thanthat at which it was turned on in the evening. It is one object of myinvention, therefore, to provide photoelectric apparatus which willoperate in one sense in response to a predetermined light value when thelight is decreasing and will operate in the opposite sense upon asubsequent increase in light when it reaches a second predeterminedvalue which is lower than the first value.

In carrying out the above object of my invention I preferably employ atime controlled device, which for example may be driven by a smallelectric motor, for effecting the proper change in the apparatus wherebyafter the illumination has been turned on in the evening in response tothe diminishing light it may be turned off in the morning in response tothe desired lower value of daylight. If the device is one having a motorwhich runs continually, such as that commonly employed in electricclocks, there is the possibility that any time lost through aninterruption in the energy supplied to the motor or the accumulated timeof several interruptions will seriously interfere with the properoperation of the apparatus. Another object of my invention is,therefore, to. provide in such apparatus means whereby such interferencewith the proper operation of the apparatus may be greatly reduced if noteliminated and a timing error due to. an interruption on one day unlessexcessive will not carry over to affect the apparatus on the next day.

My invention will be better understood from (Cl. Z50-41.5)

the following description taken in connection with the accompanyingdrawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a circuit diagram illustrating oneform of my invention; Fig. 2 is a circuit diagram illustrating a furtherdevelopment thereof; Fig. 3 is a diagram illustrating the variations indaylight and the relation thereto of the operation of the apparatusshown by Fig. 2.

In the drawing I have represented at I and 2 an alternating currentsupply circuit which, for example, may be a 60 cycle, 110 volt, lightingcircuit. Arranged to be supplied from this circuit is the artificialillumination circuit 3 to which may be connected electric lamps of anydesired form represented, for example, at 4. Circuit 3 is showncontrolled by the relay 5 having the energizing winding 6. Connected tobe supplied also from the circuit I, 2 is the transformer 8 having theprimary 9 and having the tWo secondary windings I0 and II. Secondarywinding ID is connected in circuit with the winding ll oi the relay I2and the electron discharge control device I3 which, for example, may bea Pliotron tube having the anode I4, the cathode I5, and the grid I6,the cathode being connected to be supplied with current from a portionof the winding I0. Relay I2 has the movable contact Il, the fixed frontcontact IB and the xed back contact I9. When relay I2 is in adeenergized position it completes a circuit from the supply circuit I, 2through the thermal switch 20, the winding 2I of relay 22 and theresistor 23. I'he thermal device 20 is represented as comprising theheater 24 and the bimetallic switch 25 which is arranged to be heatedthereby and which after a predetermined time closes a shunt circuitabout the heater. Ihe hand switch 26 is provided to shunt the entirethermal switch if desired. The purpose of thel thermal switch 20 is toprevent the artificial illumination from being turned on in response totemporary decreases in daylight such as might be occasioned by thepassing of a cloud or turned off in response to a temporary increase inlight such as that due to a flash of lightning.

Relay 22 has the movable contact 28 arranged to engage the iixed frontcontact 29 for the purpose of closing a holding circuit for the winding2l thereof. This relay also has the movable contact 3E! arranged toengage the fixed front contact 3| for closing the circuit of the winding6 of the relay 5, which circuit is connected to receive energy from thesupply circuit I, 2. It will be seen from the drawing that when relay I2is in its energized position, as illustrated, contacts I'I and I8 closea short circuit through the timing switch 2B around the winding 2| ofrelay 22 which relay remains open as illustrated.

Referring now to. the control circuit for the control device I3, bothends of the secondary winding II are connected with the grid I5 of thisdevice, the one end being connected therewith through the photo-electricdevice 34, which is so arranged that it is not affected by theartificial illumination, and the other end being connected therewiththrough the small capacitor 36 and resistor 37. Connected with the endsof winding II are the potentiometer 38 having the movable arm 39 and thepotentiometer 40 having the movable arm 4I. Arm 39 connects through theresistor 42 with the cathode I5 of device I3. Arm 4I connects directlywith the cathode I5 through the time switch 43. The latter switch isoperated by a timing device, preferably an electric clock, and in thedrawing is represented as being actuated by the cam 44 which is drivenby the small synchronous motor 45 supplied from the circuit I, 2. Cam 44is arranged to make one revolution per day and as shown has the highportion 45 adapted to hold the switch open and the low portion 41adapted to allow the switch to close.

The position of the various parts of the apparatus may, for example, bethat which would obtain in the afternoon when the value of daylight issuch that artificial illumination is not required. At this time thevalue of daylight reaching the photo device 34 and the setting of thepotentiometer arm 39 are such that the relay I2 is held energized by thecurrent passing the discharge device I 3, relay 22 is short-circuted andtherefore deenergized, and relay 5 also is deenergized, hence theillumination circuit 3 is open. As the value of daylight decreases inthe late afternoon or early evening, the potential of the grid I6becomes more negative or less positive relative to the cathode, as thecase may be, and at a predetermined value of daylight at which it isdesired to have artificial illumination turned on the relay I2 becomesdeenergized sufficiently to allow Contact I'I to shift from contact I8to contact I9 thus closing the circuit of relay 22 through the thermalswitch 2H. As soon as the latter switch operates, relay 22 is energized,locking itself in closed position and closing the circuit of relay 5,thereby turning on the articial illumination.

At sometime later in the evening, such for example at midnight, when theamount of daylight reaching the photo device 34 has reduced to a verylow value, the cam 44 will have been rotated to such a position that theswitch 43 will drop off the high portion of the cam and close. By thisoperation of the time switch the cathode I5 is put into direct controlof the potentiometer 49 which will be so set that the grid will berendered more positive relative to the cathode for the same degree ofdaylight. It will be noted that with the apparatus disclosed the cathodepotential is changed by the time switch rather than the grid potentialbut the effect is the same and that the connection between the cathodeand potentiometer 40 does not include a resistor such as that inconnection to potentiometer 38. Thus the former potentiometer will takeover the control of the device I3.

With potentiometer 4B now in control of device I3 and being set to causethe energization of device I3 and therefore of relay I2 in response to alower value of daylight than that at which relay I2 was previouslydeenergized, it will be seen that the artificial illumination will beturned off in the morning at a value of daylight which is lower thanthat at which the lights were turned on in the previous afternoon orevening. The cam 44 continues to rotate, and at a time which may beseveral hours after the artificial illumination has been shut off in themorning, for example, about noon time, the switch 43 will ride up on thehigh portion of the cam and interrupt the connection between the cathodeand the potentiometer 40. Thus control of the device I3 by potentiometer38 will be restored and the cycle of operation of the apparatus will becompleted.

With apparatus such as I have described above' which employs a timingswitch driven by a motor which runs continually there is the possibilitythat as a result of an interruption, say of several hours, in the supplyof energy, or of a series of interruptions which may occur on succeedingdays, the total time lost may seriously interfere with the properoperation of the apparatus. To avoid this difficulty I have provided inthe further developed form shown by Fig. 2 means whereby the motordriving the time switch runs for only a portion of the time through eachday, the motor being automatically started and stopped whereby any timelost through an interruption of the service unless it is of very longduration will not ordinarily cause an error in the operation of theapparatus to carry over from one day to the next. The apparatusdisclosed by Fig. 2 for the most part is like that shown in Fig. l. Inthis form, however, the time switch 43' is provided with two additionalmoving contacts 59 and 5!, the former being arranged to engage the fixedcontacts 52 when the switch drops off from the high portion of the camand the latter being arranged to disengage the fixed contacts 53 at thesame time. Relay 22 is provided with a back contact 55 for the movingcontact 30 thereof. 'I'his contact 55 connects with the contacts 52 ofthe time switch, and the middle contact 3| connects with the fixedcontacts 53 of the time switch.

With the apparatus in the position shown by Fig. 2 which, for example,may be in the afternoon, the circuit of the motor 45 will be closed bycontacts 5I, 53 but will be open at contacts r 30 and 3I of relay 22.The clock therefore is not running at this time and potentiometer 38 iscontrolling device I3. As the value of daylight decreases to apredetermined point in the late afternoon or early evening the photodevice causes the deenergization of relay I2 and the energization ofrelays 22 and 5 to turn on the artificial illumination as describedabove in connection with Fig. 1. The point at which the illumination isturned on may, for example, be that indicated by the point A on thecurve 6D which may be assumed to represent roughly the amount ofdaylight at various hours throughout the day. The point A is representedin the diagram, for eX- ample, as occurring at 7 P. M. By reason of theconnection between contact 3I of relay 22 and the motor 45 throughcontacts 5I and 53 the energization of relay 22 will cause the clock tostart. The speed at which the cam 44 rotates in this form of myinvention is considerably faster than that at which the cam 44 rotatedin the form shown by Fig. l. As a result of this greater speed of thecam, switch 43 will drop off of the high portion of the cam a few hourslater, for example, at midnight when the value of daylight is reduced toa value which is lower than that at which it is desired to have theillumination turned on in the following morning. The switch 43 indropping off the high portion of the cam will open the circuit of theclock motor at 5i, 53 and thus cause the clock to stop and will transfercontrol of device. i3 to potentiometer liti. On the following morningwhen daylight increases to a value at which it is desired to have theillumination turned cf, which value is represented on the diagram aspoint B occurring at fi A. M., the several relays will be operated in amanner described in connection with Fig. l to open the artificialillumination circuit 3. It will be noted that point B is considerablylower than` point A. By the deenergization of relay 22 the circuit ofthe clock motor is again established through the relay contacts 3B and5.5, it being remembered that contacts 5U and 52 of the time switch wereclosed when the switch t3 dropped cil the high portion of the cam. Theclock now ,st/arts again and runs until the switch 43 ridesrup on thehigh portion of the cam which opens the clock motor circuit at th-econtacts 5i), 52 and which restores control of device I3 topotentiometer 38. This stopping of the clock may occur at any time afterdaylight has reached a value higher than that represented by the point Aat which the lights were turned on. In the diagram it is shown occurringat about noon. The clock then remains inactive and the switch 4 alsoremains in a position, to leave potentiometer 38 in control of device I3until such time in the afternoon at which it is desired to have theillumination turned on.

While li have shown` and described the clock as coming to a stop atmidnight and again at noon, it will be understood that the actual timeof running of the clock may, if desired, be made considerably shorter,for example, by increasing the speed at which the cam is driven wherebyinterruptions that may occur in the service may be less likely to comeduring those periods in which the clock is running. Thus the clock maybe constructed to stop at l p. m. and again at 8 a. m. the onlyrequisite being that the stop at night must occur after such a time atwhich the corresponding value of daylight is somewhat less than that ofB; likewise the stop in the day time must occur after such a time atwhich the corresponding value of daylight is somewhat greater than thatof point A.

While I stated in the introductory portion of this description that acommon use of the apparatus is for turning on and oiT artificialillumination such as street lighting, it may have various other uses aswell, such as the control of electric signs. As such signs usually areturned off long before the approach of daylight, the arm 4I ofpotentiometer #tu of the present apparatus would be set so far to theleft that when switch 43 closes say at midnight device I3 would beoperated to cause the lamps 4 of the sign to be extinguished.

I have chosen the particular embodiments described above as illustrativeof my invention and it will be apparent that various other modicationsmay be made without departing from the spirit and scope of my inventionwhich modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by etters Patent of the UnitedStates, is:

1. Photoelectric relay apparatus including a photoelectric deviceadapted to be subjected to the varying intensity of daylight, saidapparatus being constructed to operate in one sense in respense to apredetermined light value when the light is diminishing, means forcausing the apparatus to operate in the opposite sense in response to alower predetermined light value when the light subsequently increasesand time controlled means for rendering said means inoperative until atime corresponding to a daylight intensity that is less than said lowerpredetermined value, means for rendering said time controlled meansinoperative at said time and means for rendering it again operative whenthe light subsequently attains said lower predetermined light value.

2. Photoeiectric relay apparatus including a photoelectric deviceadapted to be subjected to the varying intensity of daylight, saidapparatus being constructed to operate in one sense in response to apredetermined light value when the light is diminishing, means forcausing the apparatus to operate in the opposite sense in response to alower predetermined light value when the light subsequently increases, amotor controlled switch for rendering said means inoperative until atime corresponding to a daylight intensity that is less than said lowerpredetermined value, means for rendering said motor inoperative at saidtime and for rendering it again operative when the' light subsequentlyattains said lower predetermined value.

3. Photoelectric relay apparatus for controlling a lighting circuitcomprising a photoelectric device adapted to be aiTected by daylight,said apparatus being constructed to close said circuit when daylightdecreases to a predetermined value, means for causing said apparatus toopen said circuit when daylight in subsequently increasing reaches a lowpredetermined value, a motor driven switch for rendering said meansincapable of functioning until such a time at which daylight should havedecreased to a value below said lower predetermined value, meansoperative to deenergize the motor at said time and means operative tore-energize the motor when said lighting circuit is opened.

4. Photoelectric relay apparatus including a phctoelectric deviceadapted to be subjected to the varying intensity of daylight, saidapparatus being constructed to operate in one sense in response to apredetermined light value when the light is increasing, means forcausing the apparatus to operate in the opposite sense in response to ahigher predetermined light value when the light subsequently decreasesand time controlled means for rendering said means inoperative until atime corresponding to a daylight intensity that is greater than saidhigher predetermined value, means for rendering said time controlledmeans inoperative at said time and means for rendering it againoperative when the light subsequently attains said higher predeterminedlight value.

5. Photoelectric relay apparatus including a photoelectric deviceadapted to be subjected to the varying intensity of daylight, saidapparatus being constructed to operate in one sense in response to apredetermined light value when the light is increasing, means forcausing the apparatus to operate in the opposite sense in response to ahigher predetermined light value when the light subsequently decreases,a motor controlled switch for rendering said means inoperative until atime corresponding to a daylight intensity that is greater than saidhigher predetermined value, means for rendering said motor inoperativeat said time and for rendering it again operative when the lightsubsequently attains said higher predetermined value.

6. Photoelectrie relay apparatus for controlling a lighting circuitcomprising a photoelectric device adapted to be affected by daylight,said apparatus being constructed to close said circuit when daylightincreases to a predetermined value, means for causing said apparatus toclose said circuit when daylight in subsequently decreasing reaches ahigher predetermined value, a motor driven switch for rendering saidmeans incapable of functioning until such a time at which daylightshould have increased to a value above said lower predetermined value,means operative to deenergize the motor at said time and means operativeto reenergize the motor when said lighting circuit is closed.

7. Photoelectrc relay apparatus for controlling a lighting circuitcomprising a photoelectric device arranged to be affected by daylight,said apparatus being constructed to close said circuit when daylightdecreases to a predetermined value, means for causing said apparatus toopen said circuit when daylight in subsequently increasing reaches alower predetermined value and means comprising a synchronous motor and aswitch operated thereby for rendering said means incapable offunctioning until such a time at which daylight should have decreased toa value below said lower predetermined value, means operative to openthe circuit of said motor at said time and means operative to close themotor circuit when the lighting circuit is opened.

PIETER JUCHTER.

